The present invention relates to arrays for performing logic functions and more particularly it is related to testing such arrays.
The performing of logic in a matrix or an array of identical circuit elements each located at a unique intersection of an input and output line in a grid of input and output lines is well known. One very desirable arrangement for addressing such an array uses a plurality of decoders to generate interrogation signals for the input lines of the array from input variables supplied to the decoders. Difficulty has been experienced in testing arrays addressed in this manner because, for each combination of input variables, each of the decoders interrogates one of the input lines of the array. Therefore the signals on the output lines of the array are a result of simultaneous interrogation of a number of input lines and it is difficult to determine whether the output signals from the interrogation of any one line are proper. Of course the arrays could be checked by storing the desired output signal for each possible combination of input variables. However this method would require storing a very large number of output signal combinations for each different array configuration manufactured.